Stabilized energetic water-in-oil emulsion composition

ABSTRACT

A stabilized water-in-oil energetic emulsion composition comprising a) an aqueous oxidizer phase comprising at least one oxygen supplying component; b) an organic phase comprising at least one organic fuel; c) an emulsifying amount of at least one emulsifying agent suitable for forming a water-in-oil emulsion; and d) an emulsion stabilizer comprising a hydrocarbon polymer, said hydrocarbon polymer having {overscore (M)} n  ranging from about 2,000 to about 6,000, provided that said emulsion composition is essentially free of any polyvalent inorganic agent that is capable of cross-linking with the emulsifying agent or the emulsion stabilizer.

This application claims benefit of provisional application 60/245,339filed Nov. 2, 2000.

FIELD OF THE INVENTION

This invention relates to stabilized water-in-oil emulsion compositions,and more particularly to stabilized energetic water-in-oil emulsionscomprising a continuous organic phase, a discontinuous aqueous phase,emulsifiers, and a hydrocarbon polymer, said compositions havingimproved storage stability.

BACKGROUND OF THE INVENTION

Emulsion explosives have become an increasingly important productoffering in commercial mining, quarrying and construction as well asproviding potential benefits to the military. A significant qualityissue in this area of technology is maintenance of performance of thecompositions over extended periods of time.

Explosives, propellants and munitions often are stored for extendedperiods of time under a wide variety of conditions, e.g., temperature,humidity, etc. Performance of the emulsions can be adversely affected ifprecautions are not taken to insure stability of the emulsion. Moreover,higher performance materials often require the addition of solidmaterials such as aluminum metal or glass to the basic emulsion. Thesematerials tend to add further internal stress to the emulsion.

Improved surfactants and coating agents have led to improved shelf life,but the issue has not been satisfactorily resolved in all cases,especially in the case of high performance compositions. Accordingly,the industry is continuing to search for ways to improves emulsionstability.

Water-in-oil emulsions typically comprise a continuous organic phase anda discontinuous aqueous phase. Energetic emulsion compositions such asexplosive emulsions and propellant emulsions contain water and anoxygen-supplying source such as ammonium nitrate in the aqueous phase,the aqueous phase being dispersed throughout the continuous organicphase which comprises an organic fuel. Energetic emulsion compositions,for example explosive emulsions, are known to those skilled in the art.Cap-sensitive explosive emulsions are water-in-oil explosive emulsionswhich can be detonated without the use of a booster. Such emulsionexplosives are also known to those skilled in the art. Propellantemulsions such as rocket propellants are also known.

U.S. Pat. No. 3,130,096 discloses a propellant composition in which amixture of diglycidyl ethers is cured to form a binder which is admixedwith an oxidizer material. The binder also functions as a fuel.

U.S. Pat. No. 3,177,101 discloses a gas-generating composition proposedby mixing a carboxyl terminated liquid polyester with ammonium nitratepowder and a curing agent. The curing agent reacts with the carboxylportion of the liquid polyester, and the material sets to a solidconsistency. The patent distinguishes between gas-generatingcompositions, propellants, and explosives by noting that gas-generatingcompositions have a substantially lower burning rate than conventionalpropellants, just as propellants have a substantially lower burning ratethan explosives.

U.S. Pat. No. 3,790,416 discloses a composite propellant composition inwhich dewetting of the propellant composition under applied stress issubstantially reduced. Reduced dewetting is achieved through the use ofpoly-functional amines which are capable of forming a chemical bondbetween the oxidizer (oxygen-containing ammonium salt) and the binder inthe cured propellant. The composite propellant composition comprisesoxidizers and optionally fuels in the form of small solid particlesuniformly distributed in a polymeric binder.

U.S. Pat. No. 4,104,092 discloses gelled explosive compositions whichare sensitized with water-in-oil explosive emulsions. The gelledexplosive compositions basically comprise an aqueous solution ofoxidizers, fuels and sensitizing agents which have been gelled with oneor a variety of aqueous gelling agents such as guar gum and a suitablecross-linker. The patented compositions are distinguished fromwater-in-oil emulsion explosives in that emulsion explosives arecomprised of two distinct phases, the carbonaceous oil being thecontinuous phase and the aqueous solution of the oxidizing agents beingthe discontinuous phase of the emulsion.

U.S. Pat. No. 4,216,040 discloses an inverted phase or water-in-oilblasting composition having a water-immiscible liquid organic fuel as acontinuous phase, an emulsified aqueous inorganic oxidizer salt solutionas a discontinuous phase, and an organic cationic emulsifier having ahydrophilic portion and a lipophilic portion, wherein the lipophilicportion is an unsaturated hydrocarbon chain. Thickening andcross-linking agents are not necessary for stability andwater-resistancy. However, such agents can be added if desired. Theaqueous solution of the composition can be rendered viscous by theaddition of one or more thickening agents of the type and in the amountcommonly employed in the art. Such thickening agents includegalactomannin (preferably guar gums); guar gum of reduced molecularweight, biopolymer gums, polyacrylamide and analogous syntheticthickeners, flours, and starches. Cross-linking agents for cross-linkingthe thickening agents also are well known in the art. Such agents areusually added in trace amounts and usually comprise metal ions such asdichromate or antimony ions. The liquid organic, which forms thecontinuous phase of the composition, also can be thickened, if desired,by use of a thickening agent which functions in an organic liquid.

U.S. Pat. No. 4,343,663 discloses self-supporting, water-bearingexplosive products which contain discreet cells of an aqueous solutionof an inorganic oxidizing salt and/or an amine salt encapsulated by across-linked (thermoset) resin matrix.

U.S. Pat. No. 4,420,349 describes a two-component emulsion explosivecomposition consisting of a continuous oil/fuel phase and adiscontinuous oxidizer salt phase and, as an emulsifier, a dimer acidglyceride wherein the dimer acid has a carbon chain length of C18-C60.The composition is said to demonstrate superior properties of longperiod storage stability and sensitivity.

U.S. Pat. No. 4,473,418 discloses an emulsion explosive compositionwhich may include thickening and/or cross-linking agents. The typicalthickening agents include natural gums, such as guar gum or derivativesthereof, and synthetic polymers, particularly those derived fromacrylamide. Water-insoluble polymeric or elastomeric materials, such asnatural rubber and synthetic rubber, may be incorporated into the oilphase. The cross-linking agents are not further specified.

U.S. Pat. No. 4,525,225 discloses a solid water-in-oil emulsionexplosive comprising a discontinuous emulsion phase formed of an aqueoussolution of an oxidizer salt and a continuous emulsion phase formed of asolid carbonaceous fuel derived from an oleaginous liquid.

U.S. Pat. No. 4,708,753 discloses that emulsion explosives may containwater phase or hydrocarbon phase thickeners such as guar gum,polyacrylamide, carboxymethyl or ethyl cellulose, biopolymers, starches,elastomeric materials and the like as well as cross-linkers for thethickeners, such as potassium pyroantimonate and the like.

U.S. Pat. No. 4,822,433 discloses an explosive emulsion compositioncomprising a discontinuous phase containing an oxygen-supplyingcomponent and an organic medium forming a continuous phase wherein theoxygen-supplying component and organic medium are capable of forming anemulsion which, in the absence of a supplementary adjuvant, exhibits anelectrical conductivity measured at 60° C., not exceeding 60,000picomhos/meter. The conductivity may be achieved by the inclusion of amodifier which also functions as an emulsifier.

U.S. Pat. No. 4,936,932 relates to an explosive emulsion compositioncomprising a discontinuous oxidizer phase and a continuous fuel phasecomprising an aromatic hydrocarbon compound. The composition essentiallycontains as the emulsifying agent a polyisobutylene succinic anhydridebased compound in admixture with 1-4 sorbitan and oleic acid. Thecomposition is said to demonstrate high explosive strength and excellentstability.

U.S. Pat. No. 5,244,475 discloses an emulsion composition with apolymerizing and/or cross-linking agent and method for its use inimproving the manufacturing, packaging, transporting, storage placementand blasting characteristics of explosives containing an emulsion. Morespecifically, compositions and methods directed to controlling therheology of an emulsion or explosive containing an emulsion bypolymerizing and/or cross-linking the continuous phase of the emulsionby employing hydroxy-terminated polybutadiene and polymerization agentsand/or maleic anhydride adducted polybutadiene and cross-linking agents,but without compromising the integrity of the explosive reaction.

U.S. Pat. No. 5,401,341 relates to a water in oil emulsion explosivecontaining an oxidizing material in the discontinuous water phase, andthe continuous oil phase acts as a carbonaceous fuel. The patent relatesto such explosives in which polyfunctional carboxylic acids, sulfonicacids, or phosphorous-containing acids, soluble in the oil phase arecaused to cross-link using an inorganic cross-linker, thereby causingthe viscosity of the emulsion to increase.

U.S. Pat. No. 5,936,194 describes thickened emulsion compositionscomprising a discontinuous oxidizer phase, continuous fuel phase, anemulsifier and a thickener composition comprising a carboxy-containingpolymer and a promoter selected from the group consisting of sodiumthiocyanate and thiourea.

European Patent application EP 561,600 A discloses a water-in-oilemulsion explosive in which the emulsifier is the reaction product of asubstituted succinic acylating agent, having at least 1.3 succinicgroups per equivalent weight of substituents, with ammonia and/or anamine. The substituent is a polyalkene having an number averagemolecular weight of greater than 500 and preferably 1300-1500.

It is an object of the present invention to provide a stabilized waterin oil emulsion composition that can be stored for an extended period oftime without undergoing deterioration that adversely affectsperformance.

SUMMARY OF THE INVENTION

According to the present invention, a stabilized water-in-oil energeticemulsion composition is provided comprising a) an aqueous oxidizer phasecomprising at least one oxygen supplying component; b) an organic phasecomprising at least one organic fuel; c) an emulsifying amount of atleast one emulsifying agent suitable for forming a water-in-oilemulsion; and (d) an emulsion stabilizer comprising a hydrocarbonpolymer, said hydrocarbon polymer having {overscore (M)}_(n) rangingfrom about 2,000 to about 6,000, provided that the organic phase of saidemulsion composition is essentially free of any polyvalent inorganicagent that is capable of cross-linking with the emulsifying agent or theemulsion stabilizer. In one embodiment, the hydrocarbon polymer is anacylated hydrocarbon polymer. The invention also relates to methods forpreparing stabilized energetic emulsions.

DETAILED DESCRIPTION OF INVENTION

As defined herein, a stabilized emulsion composition is one that resistsdeterioration in performance during storage. Typically, this means that,under storage conditions, the emulsion composition does not undergophysical or chemical changes that adversely affect its performance.

It must be noted that as used in this specification and appended claims,the singular forms also include the plural unless the context clearlydictates otherwise. Thus the singular forms “a”, “an”, and “the” includethe plural; for example “a monomer” includes mixtures of monomers of thesame type. As another example the singular form “monomer” is intended toinclude both singular and plural unless the context clearly indicatesotherwise.

The term “lower” as used herein in conjunction with terms such as alkyl,alkenyl, alkoxy, and the like, is intended to describe such groups whichcontain a total of up to 7 carbon atoms.

This invention relates to emulsion compositions in which an aqueousphase is dispersed in a continuous organic phase by use of anemulsifier, and which further comprises a hydrocarbon polymer,preferably an acylated hydrocarbon polymer, as described in greaterdetail hereinbelow. The aqueous phase comprises water and an oxygensupplying component. The organic phase comprises at least one organicfuel.

Aqueous Phase

The aqueous phase of the inventive emulsion composition is thediscontinuous phase. The aqueous phase comprises an oxygen supplyingcomponent. The oxygen supplying component frequently comprises inorganicoxidizer salts. Such salts include ammonium, alkali metal and alkalineearth metal nitrates, chlorates, and perchlorates and mixtures of thesesalts. In one embodiment, inorganic oxidizer salts comprise,principally, ammonium nitrate, although up to about 25% by weight of theoxidizer phase can comprise either another inorganic nitrate (e.g.,alkali or alkaline earth metal nitrate) or an inorganic perchlorate(e.g., ammonium perchlorate or an alkali or alkaline earth metalperchlorate) or a mixture thereof.

In another embodiment, the composition is a melt-in-fuel emulsion. Insuch emulsions, the discontinuous oxidizer phase comprises a mixture ofoxidizer salts melted and used to form an emulsion much like that formedusing aqueous solutions of the oxidizer salts. The oxidizer melt mayinclude nonaqueous materials which decrease the melting point of theoxidizer salt mixture. Various eutectic combinations of oxidizer saltsmay be used. In addition to the salts, other ingredients may be added tothe oxidizer melt such as the perchlorate adducts of amines, ureanitrate, urea perchlorate, nitroguanidine, guanidine nitrate andguanidine perchlorate. Occasionally polyols such as ethylene glycol andglycerol may be added to the molten inorganic oxidizer salts. Whenglycols are used, in addition to lowering the melting point of thesalts, they become part of the fuel for the explosive reaction.Melt-in-fuel emulsion explosives are the subject of numerous patents,and the method of forming suitable melts of oxidizer salts, as well asforming emulsions of such melts in a continuous oil phase are well knownto those skilled in the art.

The discontinuous phase is preferably present at a level in the range offrom about 70%, often from about 90% up to about 98%, often up to about95% by weight, frequently from about 80% to about 90% by weight basedupon the total weight of the emulsion. The inorganic salt is usuallypresent at a level from about 70% to about 95% by weight, preferablyfrom about 85% to 92% by weight, and more preferably from about 87% toabout 90% by weight based on the total weight of the aqueous oxidizerphase.

Organic Phase

The organic phase is the continuous phase of the emulsion. It comprisesat least one material that serves as an organic fuel. The organic fuelis frequently a hydrocarbon, the hydrocarbon acting as a carbonaceousfuel. Most hydrocarbons are useful in the compositions of thisinvention, for example, paraffinic, olefinic, naph-thenic, aromatic,saturated or unsaturated hydrocarbons, and typically are in the form ofan oil or a wax or a mixture thereof. The fuel typically is awater-immiscible, emulsifiable hydrocarbon that is either liquid orliquefiable at a temperature of up to about 95° C., and preferablybetween about 40° C. and about 75° C.

Oils from a variety of sources, including natural and synthetic oils andmixtures thereof can be used. The oil that is useful in the inventiveemulsions can be a hydrocarbon oil having viscosity values from about 20SUS (Saybolt Universal Seconds) at 100° F. to about 2500 SUS at 100° F.Mineral oils having lubricating viscosities (e.g. SAE 5-90 grade) can beused.

Examples of useful oils include a white mineral oil available from WitcoChemical Company under the trade designation KAYDOL®; a white mineraloil available from Shell under the trade designation ONDINA®; and amineral oil available from Pennzoil under the trade designationN-750-HT®. Diesel fuel (e.g., Grade No. 2-D as specified in ASTM D-975)can be used as the oil.

Natural oils include animal oils and vegetable oils (e.g., castor oil,lard oil) as well as solvent-refined or acid-refined mineral lubricatingoils of the paraffinic, naphthenic, or mixed paraffin-naphthenic types.Oils of lubricating viscosity derived from coal or shale are alsouseful.

Synthetic lubricating oils may be used. These include hydrocarbon oilsand halo-substituted hydrocarbon oils such as polymerized andinterpolymerized olefins (e.g., polybutylenes, polypropylenes,propylene-isobutylene copolymers, chlorinated polybutylenes, etc.);alkyl benzenes (e.g., dodecylbenzenes, tetradecylbenzenes,dinonylbenzenes, di-(2-ethylhexyl)benzenes, etc.); polyphenols (e.g.,biphenyls, terphenyls, etc.); and the like. Alkylene oxide polymers andinterpolymers and derivatives thereof where the terminal hydroxyl groupshave been modified by esterification, etherification, etc., constituteanother class of known synthetic lubricating oils. These are exemplifiedby the oils prepared through polymerization of ethylene oxide orpropylene oxide, the alkyl and aryl ethers of these polyoxyalkylenepolymers.

Another suitable class of synthetic lubricating oils useful as organicfuels comprises the esters of dicarboxylic acids (e.g., aromatic acids,aliphatic acids, dimer acids, etc.) with a variety of alcohols (mono-and polyols). Specific examples of these esters include dibutyl adipate,di(2-ethylhexyl)sebacate, di-n-hexyl fumarate, dioctyl sebacate,diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecylphthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic aciddimer, the complex ester formed by reacting one mole of sebacic acidwith two moles of tetraethylene glycol and two moles of 2-ethyl-hexanoicacid, and the like.

Unrefined, refmed and re-refined oils (and mixtures of each with eachother) of the type disclosed hereinabove can be used in the emulsions ofthe present invention. Unrefined oils are those obtained directly from anatural or synthetic source without further purification treatment. Forexample, a shale oil obtained directly from retorting operations, apetroleum oil obtained directly from distillation or ester oil obtaineddirectly from an esterification process and used without furthertreatment would be an unrefined oil.

Refined oils are similar to the unrefined oils except that they havebeen further treated in one or more purification steps to improve one ormore properties. Many such purification techniques are known to those ofskill in the art such as solvent extraction, acid or base extraction,filtration, percolation, etc. Re-refined oils, also known as reclaimedor reprocessed oils, are obtained by processes similar to those used toobtain refined oils applied to refined oils which have been already usedin service. Such re-refined oils are additionally processed bytechniques directed to removal of spent additives and oil breakdownproducts.

It may be desirable to include small amounts of silicon based oils asadditives in the oil phase. These oils tend to make the composition moreresistant to moisture in the enviromnent. Useful silicon-based oilsinclude materials such as the polyalkyl-, polyaryl-, polyalkoxy-, orpolyaryloxy-siloxanes

The organic phase may contain any wax having melting point of at leastabout 25° C. and generally below 90° C., such as petrolatum wax,microcrystalline wax, and paraffin wax, mineral waxes such as ozoceriteand montan wax, animal waxes such as spermaceti wax, and insect waxessuch as beeswax and Chinese wax. Useful waxes include waxes identifiedby the trade designation MOBILWAX® 57 which is available from Mobil OilCorporation; D02764 which is a blended wax available from Astor ChemicalLtd.; and VYBAR® which is available from Petrolite Corporation.Preferred are blends of microcrystalline and paraffin waxes.

In one embodiment, the carbonaceous fuel includes a combination of a waxand an oil. In this embodiment the wax content can be at least about 25%to about 60% by weight of the oil phase, and the oil content can be atleast about 40%.

The organic phase is generally present at a level from 2%, often fromabout 5% up to about 30% by weight, often up to about 10% to 20% byweight, and frequently in the range of from about 3.5% to about 8% byweight, based on the total weight of the emulsion.

Emulsifying Agent

The emulsifying agent is one suitable for preparing water in oilemulsions. The emulsifying agent frequently comprises at least one ofhydroxy substituent groups and amino substituent groups, especiallyhydroxyalkyl and aminoalkyl substituent groups. Emulsifiers particularlysuitable for use with emulsion explosives and propellants are preferredfor use in the present invention. Especially preferred are those havinghydrophilic-lipophilic balance (HLB) ranging from 1 to about 7. Theemulsifier serves to establish an emulsion in which water dropletscontaining the oxygen supplying component are dispersed in thecontinuous organic phase. Suitable emulsifiers are stable to theconditions under which the emulsion is formed. Such emulsifiersgenerally consist of molecules with both a hydrophilic and a lipophilicportion. The lipophilic portion of the emulsifier may be eithermonomeric or polymeric in nature, provided that it contains a chainstructure of sufficient length to confer the necessary emulsificationcharacteristics. The chain structure should incorporate a backbonesequence of at least 10, and preferably not more than 500, linked atoms;these may be entirely carbon atoms, or they may be predominantly carbonatoms interrupted by heteroatoms such as oxygen or nitrogen. Desirably,the lipophilic portion includes a terminal reactive grouping, such as ahydroxyl, amino, carboxyl or carboxylic acid anhydride group, to promotelinkage of the lipophilic portion to an appropriate hydrophilic portion.

Preferred emulsifying agents comprise at least one hydrocarbylsubstituted carboxylic emulsifier composition, preferably one whereinthe hydrocarbyl group is an aliphatic group. Often, the aliphatichydrocarbyl group has {overscore (M)}_(n) ranging from about 600 toabout 5,000. Frequently, the aliphatic hydrocarbyl group is an alkenylgroup. Preferred polyalkenyl groups are derived from at least onepolymer selected from the group consisting of polybutenes, especiallypolyisobutylene, polypropylene, ethylene-propylene copolymer,ethylene-propylene-polyene copolymer and styrene-diene copolymer. Highlyunsaturated polymers may be, and frequently are, hydrogenated to reducethe amount of olefinic unsaturation present in the polymer. They areusually not exhaustively hydrogenated. In particular, ethylene-polyenepolymers and styrene-diene copolymers are frequently partiallyhydrogenated.

Preferred emulsifiers comprise at least one of esters, amides, imidesand salts. When the emulsifying agent is a polycarboxylic composition,mixtures of these such as ester-salts, ester-amides, etc are useful.

Succinic emulsifiers are preferred carboxylic emulsifying agents.Especially preferred succinic emulsifiers comprise at least one ofsuccinic ester-acid salt groups, succinic amide-acid groups, succinicdiester groups, succinic diamide groups, succinimide groups and mixturesthereof. Preferably, at least about 60% of these groups have aminoalkylor hydroxyalkyl substituents.

Succinic acylating agents useful in preparing emulsifiers includehydrocarbyl-substituted succinic acids and anhydrides which may berepresented by the formulae:

wherein R is a C₁₀ to about a C₅₀₀ hydrocarbyl group. Preferably, R isan aliphatic or alicyclic hydrocarbyl group with less than about 10% ofits carbon-to-carbon bonds being unsaturated. R may derived from olefinpolymers. R may also be derived from non-polymerized olefins of from 10to about 18 carbon atoms with alpha-olefins being particularly useful.

Succinic ester-acid salt groups may be derived from secondary ortertiary alkanol amines. Succinic amide-acid groups may be derived fromsecondary alkanol amines. Succinic diester groups may be derived fromtertiary alkanol amines. Succinic diamide groups may be derived from atleast one of primary and secondary amines. Succinimide groups may bederived from at least one of primary alkanol amine and primary alkylenepolyamines having at least one primary amino group. Succinic estergroups may be derived from polyhydroxy compounds. In a preferredembodiment, the succinic emulsifier composition is made by reaction of 1mole of at least one polyalkenyl group substituted succinic acylatingagent with from about 0.9 to about 1.1 mole of at least one secondary ortertiary alkanolarnine.

A saturated or unsaturated hydrocarbon chain derived, for example, froma polymer of a mono-olefin, the polymer chain containing from about 40to about 500 carbon atoms is useful. Suitable polyolefins include thosederived from olefins containing from 2 to 6 carbon atoms, in particularethylene, propylene, butene-1 and isoprene, but especially isobutene.Conveniently, this portion of the molecule may be provided by apoly[alk(en)yl]succinic anhydride and functional equivalents thereof.

Functional equivalents of the anhydride are materials which will reactas acylating agents in a manner similar to that of the anhydride. Theseinclude the corresponding acids, esters, usually lower alkyl esters andacyl halides

These are commercially available materials which are made by an additionreaction at an elevated temperature between a polyolefin containing aterminal unsaturated group and maleic anhydride, optionally in thepresence of a halogen catalyst. Typical poly(alk(en)yl)succinicanhydrides have a number average molecular weight in the range 400 to5000. The succinic anhydride residue in the above-mentioned compoundsprovides a convenient means of attaching the lipophilic hydrocarbonchain to the hydrophilic moiety of the emulsifier.

The use of amine salts of derivatives of substituted succinic acylatingagents as emulsifiers in emulsion explosives is disclosed in U.S. Pat.No. 4,708,753. Similarly, the alkali metal and alkaline earth metalsalts of such derivatives are usable as emulsifiers.

Especially preferred succinic emulsifiers comprise at least one ofsuccinic ester-acid salt groups, succinic amide-acid groups, succinicdiester groups, succinic diamide groups, succinimide groups and mixturesthereof.

U.S. Pat. Nos. 5,047,175; and 4,828,633 describe emulsifiers that are asalt derived from a high molecular weight carboxylic acylating agentcoupled to a low molecular weight carboxylic acylating agent. Succinicacids and anhydrides are the preferred acylating agents. U.S. Pat. Nos.5,512,079 and 5,518,517 disclose emulsion fertilizers. The emulsifiersprepared from succinic acylating agents disclosed in these four patentsare useful in the present invention.

Another suitable emulsifier is a reaction product of an aminecharacterized by the presence within its structure of at least one H—Ngroup and an intermediate formed in the reaction of at least oneolefinic compound containing at least one group of the formula

and at least one carboxylic reactant selected from the group consistingof compounds of the formulaR³C(O)(R⁴)_(n)C(O)OR⁵  (III)wherein each of R³ and R⁵ is independently H or a hydrocarbyl group, R⁴is a divalent hydrocarbylene group, and n is 0 or 1, and reactivesources thereof, and optionally, at least one aldehyde or ketone. Theseare described in U.S. Pat. No. 6.054,493 which is hereby incorporatedherein by reference for relevant disclosures in this regard.

Other suitable emulsifiers include sorbitan esters, such as sorbitansesquioleate, sorbitan monooleate, sorbitan monopalmitate, sorbitanmonostearate and sorbitan tristearate, the mono- and diglycerides offat-forming fatty acids, soybean lecithin and derivatives of lanolin,such as isopropyl esters of lanolin fatty acids, mixtures of highermolecular weight fatty alcohols and wax esters, ethoxylated fattyethers, such as polyoxyethylene(4) lauryl ether, polyoxyethylene(2)oleyl ether, polyoxyethylene(2) stearyl ether, polyoxyalkylene oleyllaurate, and substituted oxazolines such as2-oleyl-4-4′-bis(hydroxymethyl)-2-oxazoline. Suitable mixtures of suchconventional emulsifiers may also be selected. Frequently, these areused as co-emulsifiers. The co-emulsifiers comprise auxiliarysurfactants, typically having HLB ranging from 1 to about 12.

The emulsifier generally makes up between 0.5 to 2% of the totalemulsion composition. Preferably the amount of the emulsifier rangesfrom 1 to 1.5% of the total composition.

The lipophilic portion of the emulsifying agent may be a hydrocarbonchain formed by the polymerization of an olefm. Suitable olefins includeethylene, propylene, butene and hexene. However, the lipophilic portionof the molecule is not limited to polymerized olefins. More generally,the lipophilic portion of the molecule may be any hydrocarbyl groupwhich can include:

(1) hydrocarbyl groups, that is, aliphatic (e.g., alkyl or alkenyl),alicyclic (e.g., cycloalkyl, cycloalkenyl), aromatic, aliphatic- andalicyclic- substituted aromatic groups and the like as well as cyclicgroups wherein the ring is completed through another portion of themolecule (that is, any two indicated groups may together form analicyclic group);

(2) substituted hydrocarbyl groups, that is, those groups containingnon-hydrocarbon groups which, in the context of this invention, do notalter the predominantly hydrocarbyl nature of the hydrocarbyl group;those skilled in the art will be aware of such groups, examples of whichinclude ether, oxo, halo (e.g., chloro and fluoro), alkoxyl, mercapto,alkylmercapto, nitro, nitroso, sulfoxy, etc.;

(3) hetero groups, that is, groups which, while having predominantlyhydrocarbyl character within the context of this invention, containother than carbon in a ring or chain otherwise composed of carbon atoms.Suitable heteroatoms will be apparent to those of skill in the art andinclude, for example, sulfur, oxygen, nitrogen and such substituents aspyridyl, furanyl, thiophenyl, imidazolyl, etc.

In general, no more than about three non-hydrocarbon groups orheteroatoms and preferably no more than one, will be present for eachten carbon atoms in a hydrocarbyl group. Typically, there will be nosuch groups or heteroatoms in a hydrocarbyl group and it will,therefore, be purely hydrocarbyl.

The hydrocarbyl groups are preferably free from acetylenic unsaturation;ethylenic unsaturation, when present will generally be such that thereis no more than one ethylenic linkage present for every tencarbon-to-carbon bonds. The hydrocarbyl groups are often completelysaturated and therefore contain no ethylenic unsaturation. Whatever thestructure, the hydrocarbyl group provides oil solubility.

Copolymers of maleic acid or maleic anhydride with various ethylenicallyunsaturated species, such as styrene and C₂₋₃₀ alkenes are usefulemulsifying agents. Such copolymers include several carboxyl groupswithin the polymer chain. In one embodiment, these copolymers may bepartially esterified with individual alcohols (C₈ to about C₃₀) oralcohol mixtures (C₄-C₅₀). Sirnilar copolymers may be formed frommethacrylic acid, acrylic acid, crotonic acid and itaconic acid. Thecopolymers prepared with the various unsaturated acids may andpreferably will contain more than one acid group per molecule. Apoly-acid may be partially esterified to form an acid containing ester.If the partial ester is further partially reacted with a base to form apartial salt, the acid/ester in its partially salted form may serve asthe emulsifier.

The emulsifying agent is usually present in amounts ranging from about4% to about 40% based on the total weight of the organic phase.

Hydrocarbon Polymer

The emulsion compositions of this invention comprise a hydrocarbonpolymer, usually an acylated hydrocarbon polymer, said hydrocarbonpolymer having {overscore (M)}_(n) ranging from about 2,000 to about6,000. The hydrocarbon polymers include such materials as hydrogenatedpolymers of dienes, hydrogenated copolymers of a conjugated diene withvinyl substituted aromatic compounds, polymers of alpha olefinscontaining from 2 to about 28 carbon atoms, and olefin-diene copolymers.

Especially preferred hydrocarbon polymers are olefin copolymers, i.e.,polyolefins, particularly ethylene-alpha olefin copolymers.

Copolymers obtained by copolymerizing acyl group containing monomerswith hydrocarbon monomers such as olefins, polyenes, especially dienes,vinyl aromatic monomers and the like, and mixtures thereof are also wellknown. In one preferred embodiment, the polyolefin is anethylene-olefin, preferably alpha olefin, copolymer wherein the olefincontains from 3 to about 28 carbon atoms.

The acyl group of an acylated hydrocarbon polymer may be in the form ofa carboxylic acid. However, it is preferred that the acyl groups be inthe form of an anhydride or a low molecular weight ester. Methyl andethyl esters are particularly preferred esters.

Acylated hydrocarbon polymers typically contain an average of from about1 to about 6 acyl group containing monomers per polymer chain. Theacylated hydrocarbon polymer may be prepared by copolymerizing acylgroup containing monomers with hydrocarbon monomers or by grafting oneor more acyl group containing monomers onto a hydrocarbon polymer. Inone preferred embodiment, the acylated hydrocarbon polymer is anethylene-propylene copolymer having grafted thereon an average of from 1to about 6 maleic anhydride monomers per polymer chain. Such acylatedhydrocarbon polymers are commercially available, for example under thetradename LUCANT® (Mitsui Chemicals Co., Japan) and RICON® MA (RiconResins, Grand Junction Colo.).

A wide variety of acylated hydrocarbon polymers is useful based upon theaforementioned hydrocarbon polymers. The hydrocarbon polymers andacylated derivatives thereof are well known in the art and are describedin numerous patent publications including, for example, U.S. Pat. No.5,811,378 and U.S. Pat. No. 5,401,341.

Useful acyl group containing monomers include ethylenically unsaturatedcarboxylic acids or functional equivalents thereof. The most commonlyused materials contain from 2 to about 20 carbon atoms exclusive ofcarbonyl carbons. They include such acids as acrylic acid, methacrylicacid, maleic acid, fumaric acid, crotonic acid, citraconic acid,itaconic acid and mesaconic acid, as well as their anhydrides, halidesand esters (especially the lower alkyl esters, the term “lower alkyl”meaning alkyl groups having up to 7 carbon atoms). The preferredcompounds are the alpha-beta-olefinic carboxylic acids, especially thosecontaining at least two carboxy groups and more especially dicarboxylicacids, and their derivatives. Maleic acid and maleic anhydride,especially the latter, are particularly preferred.

The ethylenically unsaturated carboxylic acid is generally employed inamounts ranging from about 1 to about 6 mole per mole, based on{overscore (M)}_(n) of polymer, providing an acylated polymer containingfrom 1 to about 6 acyl groups per polymer chain.

The acylated hydrocarbon polymer is generally present in amounts rangingfrom about 0.1 to about 3% by weight based on the total weight of theemulsion composition.

Explosive Emulsions. Additional Components

Explosive emulsions typically contain other additives such assensitizing components, oxygen-supplying salts, particulate lightmetals, particulate solid explosives, soluble and partly solubleself-explosives, explosive oils and the like for purposes of augmentingthe strength and sensitivity or decreasing the cost of the emulsion.

The sensitizing components are distributed substantially homogeneouslythroughout the emulsions. These sensitizing components are preferablyclosed-cell, void containing materials, that is, particulate materialsthat comprise closed-cell, hollow cavities, for example, occluded gasbubbles which may be introduced in the form of glass or resinmicrospheres or other gas-containing particulate materials.Alternatively, gas bubbles may be generated in situ by adding to thecomposition and distributing therein a gas-generating material such as,for example, an aqueous solution of sodium nitrite. Other suitablesensitizing components which may be employed alone or in addition to theoccluded or in-situ generated gas bubbles include insoluble particulatesolid self-explosives such as, for example, grained or flaked TNT, DNT,RDX and the like, and water-soluble and/or hydrocarbon-soluble organicsensitizers such as, for example, amine nitrates, alkanolamine nitrates,hydroxyalkyl nitrates, and the like. The explosive emulsions of thepresent invention may be formulated for a wide range of applications.Any combination of sensitizing components may be selected in order toprovide an explosive composition of virtually any desired density,weight-strength, or critical diameter.

The quantity of solid self-explosive ingredients and of water-solubleand/or hydrocarbon-soluble organic sensitizers may comprise up to about40% by weight of the total emulsion. The volume of the occluded gascomponent may comprise up to about 50% of the volume of the totalexplosive emulsion.

Optional additional materials may be incorporated in the explosiveemulsions of the invention in order to further improve sensitivity,density, strength, rheology and cost of the final explosive. Typical ofmaterials found useful as optional additives include, for example,emulsion promotion agents such as highly chlorinated paraffinichydrocarbons, particulate oxygen-supplying salts such as prilledammonium nitrate, calcium nitrate, perchlorates, and the like,particulate metal fuels such as aluminum, silicon and the like,particulate non-metal fuels such as sulfur, gilsonite and the like,particulate inert materials such as sodium chloride, barium sulphate andthe like, water phase thickeners such as guar gum, polyacrylamide,carboxymethyl or ethyl cellulose, biopolymers, starches, and the like,buffers or pH controllers such as sodium borate, zinc nitrate and thelike, and additives of common use in the explosives art.

Specific examples of sensitizers and additional components are given inU.S. Pat. No. 5,401,341 which is incorporated herein by reference forrelevant disclosures in this regard.

Propellant Compositions

When the energetic emulsions of the present invention are used as rocketpropellants, it is important to slow the rate of reaction so as toproduce controlled combustion. Inadvertent inclusion of gas within theemulsion should be avoided since gas bubbles serve as sensitizers. Therate of reaction may be slowed by the use of well-known additives, orthrough the use of particulate fuels which burn more slowly than the oilused to create the emulsion. Sawdust, wood chips, nut shells, etc. aregood examples of such particulate fuels.

The emulsions may be formed by methods well known to those skilled inthe art. One common method is to mix the emulsifier with the organicphase to form an emulsifiable organic phase. The salts and other watersoluble components, if any, are mixed with water at an elevatedtemperature sufficient to cause the formation of a solution. The organicand the aqueous phases are brought together and mixed at a low shearrate to form a pre-emulsion and then at a higher rate to form the finalemulsion. The emulsion is then mixed with the acylated hydrocarbonpolymer and the resulting mixture is subjected to shearing.Alternatively, the acylated hydrocarbon polymer may be incorporated intothe organic phase before the emulsion is formed. Suspended componentssuch as sensitizers, added fuels, and added oxidizers may be added afterthe emulsion is formed.

Although the invention is not limited to a particular method of formingthe emulsion, it is generally advantageous to form the emulsion first.Often, the emulsion is formed and then stirring is continued tointroduce the hydrocarbon polymer or acylated hydrocarbon polymer intothe system. In certain cases, it is desirable to prepare the emulsion,transport it to the site where it is to be used and introduce theacylated hydrocarbon polymer.

EXAMPLE

The following example illustrates an emulsion composition of thisinvention and means for preparing it. This example is intended to beillustrative only and is not intended to limit the scope of theinvention. Unless indicated otherwise, all parts are parts by weight andtemperatures are in degrees Celsius. All analytical values are byanalysis.

An aqueous component containing 81.25 parts ammonium nitrate, 19.50parts tap water and 0.25 parts Zn(NO₃)₂, is heated with mixing to 71° C.An organic component containing 1.35 parts of a 52% in mineral oilsolution of a half-ester salt, half amide ester prepared by reactingpolyisobutenyl ({overscore (M)}_(n)) substituted succinic anhydride withdiethanol amine (the emulsifier), 0.7 parts sorbitan monooleate(co-emulsifier), 0.5 parts dioctyl adipate, 0.5 parts maleinatedpolybutadiene (LUCANT 6020H) and 3.35 parts diesel fuel oil is alsoheated with mixing to 71° C. The aqueous component (96.4 parts) ispoured, with mixing over 2 minutes, into the organic component in thebowl of a mixer with further mixing for 2 minute at high speed.

Each of the documents referred to above is incorporated herein byreference. Except in the examples, or where otherwise explicitlyindicated, all numerical quantities in this description specifyingamounts of materials, reaction conditions, molecular weights, number ofcarbon atoms, and the like, are to be understood as modified by the word“about”. Unless otherwise indicated, each chemical or compositionreferred to herein should be interpreted as being a commercial gradematerial which may contain the isomers, by-products, derivatives, andother such materials which are normally understood to be present in thecommercial grade. However, the amount of each chemical component ispresented exclusive of any solvent or diluent oil which may becustomarily present in the commercial material, unless otherwiseindicated. It is to be understood that the upper and lower amount,range, and ratio limits set forth herein may be independently combined.As used herein, the expression “consisting essentially of” permits theinclusion of substances which do not materially affect the basic andnovel characteristics of the composition under consideration.

While the invention has been explained in relation to its preferredembodiments, it is to be understood that various modifications thereofwill become apparent to those skilled in the art upon reading thespecification. Therefore, it is to be understood that the inventiondisclosed herein is intended to cover such modifications that fallwithin the scope of the appended claims.

1. A stabilized water-in-oil energetic emulsion composition comprisinga) an aqueous oxidizer phase comprising at least one oxygen supplyingcomponent; b) an organic phase comprising at least one organic fuel: c)an emulsifying amount of at least one emulsifying agent suitable forforming a water-in-oil emulsion; and d) an emulsion stabilizercomprising an acylated hydrocarbon polymer, said acylated hydrocarbonpolymer having {overscore (M)}_(n) ranging from about 2,000 to about6,000 and acyl groups selected from carboxylic acids, their anhydrides,and alkyl esters of said carboxylic acids wherein said alkyl groups have1 to 7 carbon atoms, or combinations thereof provided that the organicphase of said emulsion composition is essentially free of any polyvalentinorganic agent that is capable of cross-linking with the emulsifyingagent or the emulsion stabilizer.
 2. The composition of claim 1 whereinthe emulsifying agent comprises a composition having HLB ranging fromabout 1 to about
 7. 3. The composition of claim 1 wherein said oxygensupplying component comprises ammonium nitrate.
 4. The composition ofclaim 1 wherein the emulsifying agent comprises at least one aliphatichydrocarbyl group substituted carboxylic emulsifier composition.
 5. Thecomposition of claim 4 wherein the aliphatic hydrocarbyl group of theemulsifying agent is a polyalkenyl group derived from at least onemember of the group consisting of polybutenes, polypropylene,ethylene-propylene copolymer ethylene-propylene-polyene copolymer, andpartially hydrogenated styrene-diene copolymer.
 6. The composition ofclaim 5 wherein the polyalkenyl group is derived from polyisobutylene.7. The composition of claim 4 wherein the carboxylic emulsifiercomposition comprises a succinic emulsifier composition.
 8. Thecomposition of claim 7 wherein the succinic emulsifier comprises atleast one of succinic ester-acid salt groups, succinic amide-acidgroups, succinic diester groups, succinic diamide groups, succinimidegroups and mixtures thereof.
 9. The composition of claim 8 wherein atleast 60% of said groups have aminoalkyl and hydroxyalkyl substituents.10. The composition of claim 4 wherein the aliphatic hydrocarbyl groupof the emulsifying agent has {overscore (M)}_(n) ranging from about 600to about 5,000.
 11. The composition of claim 7 wherein the succinicemulsifier amide-acid groups derived from secondary alkanol amines. 12.The composition of claim 7 wherein the succinic emulsifier comprisessuccinic diester groups derived from tertiary alkanol amines.
 13. Thecomposition of claim 7 wherein the succinic emulsifier comprisessuccinic diamide groups derived from at least one of primary andsecondary amines.
 14. The composition of claim 7 wherein the succinicemulsifier comprises succinimide groups derived from at least one ofprimary alkanol amine and primary alkylene polyamines having at leastone primary amino group.
 15. The composition of claim 7 wherein thesuccinic emulsifier comprises ester groups derived from polyhydroxycompounds.
 16. The composition of claim 1 wherein the acylatedhydrocarbon polymer of the stabilizer comprises at least one polyolefin.17. The composition of claim 16 wherein the polyolefin is anethylene-olefin copolymer wherein the olefin contains from 3 to about 28carbon atoms.
 18. The composition of claim 17 wherein the olefin is analpha olefin.
 19. The composition of claim 1 wherein said emulsioncomposition comprises from about 0.1 to about 3 weight percent of anacylated hydrocarbon polymer.
 20. The composition of claim 19 whereinthe acylated hydrocarbon polymer is prepared by grafting acyl groupcontaining monomers onto a substantially hydrocarbon polymer.
 21. Thecomposition of claim 19 wherein the acylated hydrocarbon polymer isprepared by copolymerizing acyl group containing monomers withhydrocarbon monomers.
 22. The composition of claim 19 wherein theacylated hydrocarbon polymer is an ethylene-propylene copolymer havinggrafted thereon an average of from about 1 to about 6 maleic anhydridemonomers per polymer chain.
 23. The composition of claim 7 wherein thesuccinic emulsifier composition is made by reaction of 1 mole of atleast one polyalkenyl group substituted succinic acylating agent withfrom about 0.9 to about 1.1 mole of at least one secondary or tertiaryalkanolamine.
 24. The composition of claim 1 wherein the continuousorganic phase is present in amounts ranging from about 2% to about 10%by weight, the discontinuous aqueous phase is present in amounts rangingfrom about 90% to about 98% by weight, both based on the total weight ofthe emulsion composition, said oxygen-supplying component is present inamounts in the range of about 70% to about 95% by weight based on theweight of said aqueous phase, the emulsifying agent is present inamounts ranging from about 4% to about 40% by weight based on the totalweight of the oil phase and the emulsion stabilizer is present inamounts ranging from about 0.1 to about 3% by weight based on the totalweight of the emulsion composition.
 25. The composition of claim 1further comprising a sensitizing amount of at least one closed-cell,void-containing material.
 26. The composition of claim 1 furthercomprising a sensitizing amount of gas bubbles.
 27. A method forpreparing an emulsion explosive composition comprising 1) preparing anaqueous component comprising water and at least one oxygen supplyingcomponent; 2) preparing an organic component comprising an organic fuel,an emulsifying amount of at least one emulsifying agent suitable forforming a water-in-oil emulsion and an emulsion stabilizer comprising anacylated hydrocarbon polymer, said acylated hydrocarbon polymer having{overscore (M)}_(n) ranging from about 2,000 to about 6,000 and acylgroups selected from carboxylic acids, their anhydrides, and alkylesters of said carboxylic acids wherein said alkyl groups have 1 to 7carbon atoms, or combinations thereof; and 3) preparing an emulsion bymixing the aqueous component and the organic component.
 28. A method forpreparing an emulsion explosive composition comprising 1) preparing anaqueous component comprising water and at least one oxygen supplyingcomponent; 2) preparing an organic component comprising an organic fueland an emulsifying amount of at least one emulsifying agent suitable forforming a water-in-oil emulsion; 3) preparing an emulsion by mixing theaqueous component and the organic component, then 4) incorporating intothe emulsion an emulsion stabilizer comprising an acylated hydrocarbonpolymer, said acylated hydrocarbon polymer having {overscore (M)}_(n)ranging from about 2,000 to about 6,000 and acyl groups selected fromcarboxylic acids, their anhydrides, and alkyl esters of said carboxylicacids wherein said alkyl groups have 1 to 7 carbon atoms, orcombinations thereof.
 29. The method of claim 27 wherein said emulsioncomposition comprises from about 0.1 to about 3 weight percent of anacylated hydrocarbon polymer.